我想更新有关装饰器内部多处理的问题（我之前的问题似乎已经死了:)）。我偶然发现了这个问题，不幸的是我不知道如何解决这个问题。为了需要我的应用程序，我必须在装饰器内部使用多处理但是...当我在装饰器内使用多处理时，我得到错误：
Can't pickle <function run_testcase at 0x00000000027789C8>: it's not found as __main__.run_testcase。
另一方面，当我调用我的多处理函数时，正常函数wrapper(function,*arg)就可以了。这很棘手，但我不知道我做错了什么。我接近得出结论，这是python错误:)。也许有人知道这个问题的解决方法留下相同的语法。我在Windows上运行此代码（不幸的是）。
上一个问题：Using multiprocessing inside decorator generates error: can't pickle function...it's not found as
模拟此错误的最简单代码：
from multiprocessing import Process,Event
class ExtProcess(Process):
def __init__(self, event,*args,**kwargs):
self.event=event
Process.__init__(self,*args,**kwargs)
def run(self):
Process.run(self)
self.event.set()
class PythonHelper(object):
@staticmethod
def run_in_parallel(*functions):
event=Event()
processes=dict()
for function in functions:
fname=function[0]
try:fargs=function[1]
except:fargs=list()
try:fproc=function[2]
except:fproc=1
for i in range(fproc):
process=ExtProcess(event,target=fname,args=fargs)
process.start()
processes[process.pid]=process
event.wait()
for process in processes.values():
process.terminate()
for process in processes.values():
process.join()
class Recorder(object):
def capture(self):
while True:print("recording")
from z_helper import PythonHelper
from z_recorder import Recorder
def wrapper(fname,*args):
try:
PythonHelper.run_in_parallel([fname,args],[Recorder().capture])
print("success")
except Exception as e:
print("failure: {}".format(e))
from z_wrapper import wrapper
from functools import wraps
class Report(object):
@staticmethod
def debug(fname):
@wraps(fname)
def function(*args):
wrapper(fname,args)
return function
from z_report import Report
import time
class Test(object):
@Report.debug
def print_x(self,x):
for index,data in enumerate(range(x)):
print(index,data); time.sleep(1)
if __name__=="__main__":
Test().print_x(10)
我将@wraps添加到以前的版本
我的追溯：
Traceback (most recent call last):
File "C:\Interpreters\Python32\lib\pickle.py", line 679, in save_global
klass = getattr(mod, name)
AttributeError: 'module' object has no attribute 'run_testcase'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:\EskyTests\w_Logger.py", line 19, in <module>
logger.run_logger()
File "C:\EskyTests\w_Logger.py", line 14, in run_logger
self.run_testcase()
File "C:\EskyTests\w_Decorators.py", line 14, in wrapper
PythonHelper.run_in_parallel([function,args],[recorder.capture])
File "C:\EskyTests\w_PythonHelper.py", line 25, in run_in_parallel
process.start()
File "C:\Interpreters\Python32\lib\multiprocessing\process.py", line 130, in start
self._popen = Popen(self)
File "C:\Interpreters\Python32\lib\multiprocessing\forking.py", line 267, in __init__
dump(process_obj, to_child, HIGHEST_PROTOCOL)
File "C:\Interpreters\Python32\lib\multiprocessing\forking.py", line 190, in dump
ForkingPickler(file, protocol).dump(obj)
File "C:\Interpreters\Python32\lib\pickle.py", line 237, in dump
self.save(obj)
File "C:\Interpreters\Python32\lib\pickle.py", line 344, in save
self.save_reduce(obj=obj, *rv)
File "C:\Interpreters\Python32\lib\pickle.py", line 432, in save_reduce
save(state)
File "C:\Interpreters\Python32\lib\pickle.py", line 299, in save
f(self, obj) # Call unbound method with explicit self
File "C:\Interpreters\Python32\lib\pickle.py", line 623, in save_dict
self._batch_setitems(obj.items())
File "C:\Interpreters\Python32\lib\pickle.py", line 656, in _batch_setitems
save(v)
File "C:\Interpreters\Python32\lib\pickle.py", line 299, in save
f(self, obj) # Call unbound method with explicit self
File "C:\Interpreters\Python32\lib\pickle.py", line 683, in save_global
(obj, module, name))
_pickle.PicklingError: Can't pickle <function run_testcase at 0x00000000027725C8>: it's not found as __main__.run_testcase
答案 0 :(得分：3)
multiprocessing模块通过调用它们的pickler来调用其slave进程中的函数。这是因为它必须通过它为从属进程创建的IPC接口发送函数的名称。 pickler找出要使用的正确名称并通过它发送，然后在另一侧，unpickler将名称转换回函数。
当一个函数是一个类成员时，没有帮助就无法正确地进行pickle。对@staticmethod成员来说情况更糟，因为他们的类型为function，而不是类型instancemethod，这会欺骗挑选者。不使用multiprocessing：
import pickle
class Klass(object):
@staticmethod
def func():
print 'func()'
def __init__(self):
print 'Klass()'
obj = Klass()
obj.func()
print pickle.dumps(obj.func)
产生
Klass()
func()
Traceback (most recent call last):
...
pickle.PicklingError: Can't pickle <function func at 0x8017e17d0>: it's not found as __main__.func
当你尝试挑选像obj.__init__这样的常规非静态方法时问题会更清楚，因为pickler会意识到它确实是一个实例方法：
TypeError: can't pickle instancemethod objects
def call_name(instance, name, *args = (), **kwargs = None):
"helper function for multiprocessing: call instance.getattr(name)"
if kwargs is None:
kwargs = {}
getattr(instance, name)(*args, **kwargs)
现在而不是（这是从你的链接帖子中复制的）：
PythonHelper.run_in_parallel([self.run_testcase],[recorder.capture])
你会做这样的事情（你可能想要调用序列）：
PythonHelper.run_in_parallel([call_name, (self, 'run_testcase')],
[recorder.capture])
（注意：这都是未经测试的，可能有各种错误）。
<小时/>的更新
我拿了你发布的新代码并试了一下。
首先，我必须修复z_report.py中的缩进（缩进所有class Report）。
完成后，运行它会产生与您显示的错误完全不同的错误：
Process ExtProcess-1:
Traceback (most recent call last):
File "/usr/local/lib/python2.7/multiprocessing/process.py", line 258, in _bootstrap
self.run()
File "/tmp/t/marcin/z_helper.py", line 9, in run
Process.run(self)
File "/usr/local/lib/python2.7/multiprocessing/process.py", line 114, in run
recording
[infinite spew of "recording" messages]
修复无尽的“录制”消息：
diff --git a/z_recorder.py b/z_recorder.py
index 6163a87..a482268 100644
--- a/z_recorder.py
+++ b/z_recorder.py
@@ -1,4 +1,6 @@
+import time
class Recorder(object):
def capture(self):
- while True:print("recording")
-
+ while True:
+ print("recording")
+ time.sleep(5)
这留下了剩下的一个问题：print_x的错误论据：
TypeError: print_x() takes exactly 2 arguments (1 given)
Python实际上正在为你做所有正确的事情，只是z_wrapper.wrapper有点过分热心：
diff --git a/z_wrapper.py b/z_wrapper.py
index a0c32bf..abb1299 100644
--- a/z_wrapper.py
+++ b/z_wrapper.py
@@ -1,7 +1,7 @@
from z_helper import PythonHelper
from z_recorder import Recorder
-def wrapper(fname,*args):
+def wrapper(fname,args):
try:
PythonHelper.run_in_parallel([fname,args],[Recorder().capture])
print("success")
这里的问题是，到达z_wrapper.wrapper时，函数参数已全部捆绑到元组中。 z_report.Report.debug已经有：
def function(*args):
这样两个参数（在本例中为main.Test的实例和值10）已被制作为元组。您只希望z_wrapper.wrapper将该（单个）元组传递给PythonHelper.run_in_parallel，以提供参数。如果你添加另一个*args，那么元组被包装到另一个元组中（这次是一个元素）。 （您可以在print "args:", args中添加z_wrapper.wrapper来查看此内容。）